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Keep killing alternators

Discussion in 'Vans' started by skloon, Jul 6, 2016.

  1. skloon

    skloon New Member

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    78 b300 motorhome, every spring for the past 3 years I go out put my battery in the beast and start it and low and behold the alternator has died- why does it die when parked ??
     
  2. ImperialCrown

    Level III Supporter

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    We need more information. Is it discharging or making noise? In either case, the old alternator would likely need an autopsy for an answer.
    Quality control on reman alternators is variable. Most come with a 1 year warranty. Some stores may offer a better lifetime warranty.
    What part inside the alternator dies? Is it the same component failing every time? Brushes? Stator? Rotor? Bearings?
    Are there shorts in the battery or vehicle wiring that could damage the alternator? Is the alternator the correct size (amperage output) for the load involved?
     
  3. ka9yhd

    ka9yhd Active Member

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    Take it to a rebuild shop and let them find out what died inside the alternator. Just replacing the alternator with another reman alternator will not tell you anything. You will never know if there is something causing the problem or was it a poor job of a rebuild of the alternator.
     
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  4. dana44

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    At the same time, if I have this right, you put the motorhome up for the winter and pull the battery cable so it doesn't go dead from sitting, are you sure the alternator is still functioning when she is put up for the winter? The charging system problem may be something else causing it to go bad, such as a voltage regulator or a converter (if you have one set up with it, being a motorhome), and the alternator is actually overheating/overcharging and then sitting during the winter an overheated/heat damaged part corrodes to the point of instant failure when electricity is put to it after sitting.
     
  5. skloon

    skloon New Member

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    I have a 'lifetime' warranty on the alternator but I will take this one and get it checked- I pull both batteries and only put the starting battery in- the thing spins but doesn't put out a charge- I will probably change the voltage regulator too as it came with a couple of spares
     
  6. ImperialCrown

    Level III Supporter

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    Have them bench test the alternator for output. Does the ammeter in the instrument cluster work? The bulkhead (firewall) connectors on these vans had problems with poor connections getting hot and melting plastic.
    The ammeter/shunt is part of the charging circuit.
    Put a voltmeter across the battery terminals for some charging system diagnostics.
    Stock74upb.gif
     
  7. skloon

    skloon New Member

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    Had it tested not putting out anything at all-I am going to check the bulkhead, thanks for the diagram it makes more sense than the schematic
     

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